Our extended evaluation of the safety and efficacy of cingulotomy will involve psychiatric evaluations, neurological examinations, and neuropsychological assessments in five groups of subjects. There will be two experimental groups and three control groups. The two experimental groups comprise patients with chronic pain who undergo cingulotomy, and patients with severe psychiatric disease who undergo cingulotomy; the three control groups comprise patients with chronic pain who receive various peripheral treatments; patients with severe psychiatric disease who do not undergo brain surgery, and normal control subjects. In the expectation of achieving a better understanding of these patients' conditions and of the mechanisms by which improvement occurs, or the reasons that it does not occur, we shall search for: Short-term and long-term changes in each patient's disease or complaint by comparing the psychiatric assessment done just before operation or other treatment with those obtained soon after and several years later. Short-term and long-term changes in neurological status revealed by detailed neurological examinations performed just before operation or other treatment, soon after, and several years later in the same patients. Short-term and long-term changes in certain quantifiable capacities associated with limbic mechanisms, including pain perception, olfactory perception, behavioral correlates of motivation and affect, memory function, and spatial capacities. Our study of cingulotomy is unique in six ways: (1) independence from the referring neurosurgeon and his hospital; (2) the large number of patients; (3) the rigor of the psychiatric evaluation; (4) the inclusion of a detailed neurological examination; (5) the verification of lesions by CT scan; and (6) the wide range of quantitative behavioral tasks. The direct application of our work is to improve prognosis and management in adults suffering from chronic pain or psychiatric disease.